'teammate' originates from the combination of 'team' and 'mate', where 'team' meant 'a group of people working together' and 'mate' meant 'companion'.

'teammate' evolved from the Old English word 'team' and the Middle English word 'mate', eventually becoming the modern English word 'teammate'.

Initially, it meant 'a companion in a group', and this meaning has largely remained the same in modern usage.